No Response Errors

Please read this entire article before you start
troubleshooting.

This error indicates that the hand control is unable to communicate with
another system component, for example, 16 and 17 are the motor control processors located inside the mount. One source for
this error is faulty power, either low voltage (weak batteries) or a loose
connector. Read
this
for suggestions regarding power.

If you receive a "No Response 1" error when checking
version, read
this.

One recently appearing problem is for those with an older NexStar GPS.
The newest versions of the hand control - version 4 or higher - require
motor control firmware version 4 or higher. If you have older motor
control firmware, the hand control will display the no response error.
See
this article for details on GPS firmware versions and upgrading when
necessary.

On rare occasions, the motor control may be stuck in "boot mode".
Fixing the problem requires you reload the latest motor control firmware -
follow
these instructions.

Many times the problem is the connector that the hand control plugs in to.
Try connecting the hand control to one of the AUX jacks (for mounts with an AUX
jack), rather than
the normal hand control jack. Also, the pins on the jack or the plug can
accumulate slight amounts of corrosion that can interrupt the low voltage
signals. These can be easily cleaned with contact cleaner available at
electronics parts stores. Do not over do it, you do not want excess cleaner
to short out the electrical connections. Be sure the power is off and use
a cotton swab dampened with contact cleaner to rub any contaminants from the
connectors. Also, take a good look at the pins and insure they are
not bent or misaligned.

Another potential problem area is that the plastic RJ-12 connector
(phone-type connector) on the end of the coiled cable might need to be
re-crimped or replaced. Or, occasionally the connection of the coiled
cable inside the hand control has worked loose and causes No Response
errors. This can be fixed by carefully removing the back of the hand
control (6 screws hold it on) and reseating the connector.

If power or the hand control connectors are not the problem, there may be a
faulty connection inside the base.

For the NexStar 8/9.25/11 GPS, start by disconnecting the power from the
telescope. Using a 3/16 inch hex wrench, remove the two bolts securing the
handle to the left fork arm. Using a 9/64 inch or 3.5mm hex wrench, remove
the plastic covering on the left fork arm. Remove and reseat all connector
cables attached to the small motor control circuit board - this usually wipes
off any accumulated corrosion or re-establishes lost connections. Be very
careful not to misalign the pins and the connectors or damage may result.
Replace the cover and the handle and test the telescope.

If you still experience problems, there may be a connector loose under the
panel on the base of the scope. Using a 9/64 inch or 3.5mm hex wrench, remove
the five bolts on the top of the base panel. In a well-lit space, slowly raise
the panel, being careful not to pull any of the cables loose. With the panel
raised about 2 inches (rolled-up socks are a good way to prop it up), reseat all
connector cables you can easily reach. Reseat the panel and secure the five
bolts.

For the NexStar 5i/8i/8i Special Edition and the SE series, open the battery cover and remove the four screws
securing the base cover. Carefully lift the base cover, noting there is a
cable running from the battery holder to the base. You may find on your
scope that you also need to loosen or remove the two lower screws on the plastic
cover on the inside of the fork arm. On some scopes it may even be
necessary to remove the optical tube and then completely remove the cover on the
inside of the fork arm. This is not a terribly difficult task - but I
won't describe it here. You will find details in the instructions for
Ray's Brackets at
www.buyastrostuff.com or in the Maintenance chapter of the
NexStar User's Guide. After
removing the base cover, remove and reseat all
connector cables attached to the circuit boards. Be very careful not to
misalign the pins and the connectors or damage may result. Replace the
cover and test the telescope.

For the NexStar GT, NexStar SLT and Celestron StarGuide, open the fork arm (remove the plastic outer cover) and
remove and reseat all connector cables attached to the circuit boards. Be
very careful not to misalign the pins and the connectors or permanent damage to
the circuitry may result.
Replace the cover and test the telescope.

Similar procedures might fix this problem on the CPC, LCM, CGE, CGE Pro, CGEM and Advanced Series with
GoTo (AS-GT)
models as well. Also, there is a problem on some AS-GT mounts regarding
insulation between the bottom of the motor control board and the mount.
Peter Bruce has written an article describing the problem and the fix.
Click here to download
the article in Adobe Acrobat format (reader available from
www.adobe.com).